Human skin is a permeable membrane. It is characterized by thousands of pores which function as openings for sebaceous (oil producing) and eccrine (sweat-producing) glands located beneath the skin. Each pore communicates with a corresponding gland by means of a hollow tube, otherwise known as the pilary canal. According to this configuration, a pore functions as an exit portal for internally produced sebaceous and sweat gland products such as sebum (oil) and perspiration. Skin pores also represent entry portals for externally applied substances, including lotions, creams and cosmetic preparations. It is generally understood that human skin represents a changing, dynamic environment where the exit and entry of substances can significantly influence pore size and visibility.
Pores associated with sweat glands are very small. There are no aesthetic considerations because these skin surface openings are not visible without a magnifying lens. The present invention is directed to the size and visibility of skin pores that communicate with more troublesome sebaceous glands. These pores provide the situs for surface acne which creates a coarse and uneven appearance on the skin.
Skin pores (and sebaceous glands) are large and numerous on the face and scalp, coincidentally the areas of maximum exposure on the skin. For facial areas the density ranges from 400 to 800 pores/cm.sup.2, compared with 50 pores/cm.sup.2 on the arms and legs. The forehead, nose and nasolabial folds are the areas of highest pore concentration.
Pores, like wrinkles, have a defined size which is susceptible to measurement. But, the visual appearance of skin pores partially depends on the texture of surrounding surfaces. A rough, dry condition scatters light in a manner which emphasizes openings on the skin surface. In contrast, smooth skin reflects incident light to reduce the appearance of surface irregularities created by pores or openings. When a pore is surrounded by rough, debris-laden skin it is more noticeable and appears larger.
In scientific terms, the skin pore of interest is known as a "follicular orifice." The orifice or pore cooperates with a sebaceous follicle characterized by a small, hair-producing portion, a deep pilary canal and a multilobular sebaceous gland that secretes its product (sebum or "oil") into the base of the canal.
The upper most portion of the pilary canal is lined with a layer of "horny cells" which are constantly replaced and shed into the canal. Under normal circumstances, the displaced cells mix with sebum that flows through the canal and onto the skin surface. This dynamic process of descaling and cleansing with sebum occurs on a continuous basis.
Pore size is largely determined by genetic, environmental and physiological factors. It is generally understood that pore diameter is proportionate to the size of sebaceous glands beneath the skin. A good correlation is recognized between pore size and oil-producing activity. Large pores (orifices) create a coarse, uneven complexion which generally detracts from the appearance o an individual.
Increased pore size is frequently associated with hyperactive sebaceous glands. This condition generates larger amount of sebum which expands the pilary canal and dilates pore diameter to accommodate greater internal pressure. By limiting sebum production and/or facilitating sebum removal, the compositions of the present invention minimize pore size and improve overall appearance.
It will also be appreciated that the sebaceous follicle may produce cells which do not shed as fine, discrete particles. When this condition occurs, the cells accumulate, coagulate with sebum, mix with other skin materials and "plug" the pore opening. This aberration disrupts the normal environment of cellular shedding and cleansing with sebum secretions. It also leads to an accumulation of cellular debris, enlargement of the attendant pore and greater visibility on the skin surface.
The aging process further increases pore size and visibility. During adolescence, larger pores are generally attributed to increased glandular activity and higher sebum production which causes canal blockage and pore expansion. As the aging process continues, sebum production gradually declines and the shedding of "horny cells" slows down. These conditions cause an accumulation of debris which increases the size and visibility of individual pores.
The aging process also causes deterioration of the dermal elements surrounding the follicle. These changes are manifested by internal collapse of supporting skin structure and expansion of the follicular canal. The ultimate result is pore dilation and greater visibility on the skin surface.
The skin pore reducer of this invention prevents accumulation of oil and other debris in the pilary canal, at the pore opening and on the surrounding skin surface. This cleansing technique "shrinks" the pore and minimizes visibility on the skin surface.
Numerous art-recognized compositions have attempted to absorb oil and facial debris from skin surfaces and attendant pore structures. Examples of these products are described in Groller U.S. Pat. No. 4,933,177 and Elliott U.S. Pat. No. 4,954,532. But, the prior art has not identified or addressed the multiple causes of skin pore enlargement.